如何在没有itertools的情况下替换itertools.product？

def product(*args):
    pools = [tuple(pool) for pool in args]
    result = [[]]
    for pool in pools:
        result = [x+[y] for x in result for y in pool]
    for prod in result:
        yield tuple(prod)

for item in product([1, 2], ['a', 'b', 'c'], ['x', 'y']):
    print(item)

(1, 'a', 'x')
(1, 'a', 'y')
(1, 'b', 'x')
(1, 'b', 'y')
(1, 'c', 'x')
(1, 'c', 'y')
(2, 'a', 'x')
(2, 'a', 'y')
(2, 'b', 'x')
(2, 'b', 'y')
(2, 'c', 'x')
(2, 'c', 'y')